Shears, being everyday objects, have received significantly less attention by archaeometallurgists than other edged tools or weapons. Yet, shear blades were forged with the same techniques as blades of, e.g. knives and swords. The most common shear type in ancient times was the bow shears, where the bow had to be flexible so it could be repeatedly bent without cracking or breaking. The shear-maker, therefore, faced the challenge of combining hard steel (the blades) with soft/flexible steel (the bow). In fact, bow shears are one of the first tools to be invented, where metal acts as a spring. Thus, ancient bow shears can be used for investigating the history and development of spring steel technology, which is currently unclear. Here, we present the metallurgical characterization of two 11th -12th c. single-bow shears from Sigtuna, Sweden. Both the blades and the bows of the two shears were found to be of decent quality and much better than in older shears from the Roman period. Although the steel qualities are not quite up to modern standards, this does not in itself prove that the Sigtuna blacksmiths lacked the technological knowledge to make ideal spring steel. Shears are relatively cheap everyday objects intended to be used until they break, at which point they are discarded. Therefore, it might not have been worth the Medieval blacksmiths' time and effort to perfect the material properties of steel used in shears. The shears' blades are on par with Medieval-period knife blades, and future studies on ancient shear-making should preferably involve comparisons of shears and knives from the same origins.

Vraket av ett drygt 20 meter långt och knappt 8 meter brett klinkbyggt lastfartyg påträffades under 2017 i Stockholms mellersta skärgård. Trots att skrovet har kollapsat i såväl fören som aktern är vraket ovanligt välbevarat.

29 iron rings with diameters between 9 and 15 cm were excavated in 1989 at a Vendel Period settlement site with a longhouse, located at Aselby in Dalecarlia, Sweden. Most of the rings had between one and three smaller rings attached. Rings of this type and size are fairly common at Scandinavian Vendel and Viking Period sites - settlements, cemeteries and cult precincts - but their function remains debated. The rings from Aselby have been interpreted as iron/steel bars, to be used or traded as raw material for e.g. weapons production. Previous metallurgical analysis of one Aselby ring showed it to consist of somewhat uneven but still decent-quality carbon steel. General conclusions should however not be drawn from a single observation. Here, we have sampled six Aselby rings for metallographic examination of the cross-sections. The material quality and carbon content of the sampled rings were found to be very uneven, and relatively large inclusions of unworked slag were common. We conclude that the rings were not bars of raw material. Instead, they may have been amulet rings, intended for ritual use. If so, our results suggest that the material properties of amulet rings may have been less important during rituals it may have sufficed that the rings had the right shape.

This study focuses on the oxidation of water atomized metal powders. Pilot plant experiments were performed using liquid iron alloyed with manganese and carbon. The powder particle shape and the oxides were determined using optical and scanning electron microscopy with energy dispersive X-ray microanalysis. The oxygen in the atomized powders was mainly present as thin surface oxide layers, which were determined to increase from 10 to 40-60 nm, at increased particle sizes from 10 to 750 mu m. In addition, manganese oxides were observed to be unevenly distributed at the surface of several particles for iron powders alloyed with 0.3mass% Mn. Experimental data indicated that between 10 and 20% of the manganese was present as oxides in the powders. However, equilibrium calculations predicted a strong driving force for oxidation of manganese. More specifically, it was estimated that only 4% of the initial manganese content remained in the final atomized powders.

Alloy 718, ATI 718Plus® and Waspaloy have been investigated in terms of what their respective solidification process reveals. Differential thermal analysis was used to approach the task together with secondary electron and back scattered electron detectors equipped with an energy dispersive X-ray spectroscopy detector. These experimental methods were used to construct pseudo binary phase diagrams that could aid in explaining solidification as well as liquation mechanisms in processes such as welding and casting. Furthermore, it was seen that Waspaloy has the smallest solidification range, followed by Alloy 718, and finally ATI 718Plus® possessing the largest solidification interval in comparison.

Alloy 718, ATI 718Plus (R) and Waspaloy have been investigated in terms of what their respective solidification process reveals. Differential thermal analysis was used to approach the task together with secondary electron and back scattered electron detectors equipped with an energy dispersive X-ray spectroscopy detector. These experimental methods were used to construct pseudo binary phase diagrams that could aid in explaining solidification as well as liquation mechanisms in processes such as welding and casting. Furthermore, it was seen that Waspaloy has the smallest solidification range, followed by Alloy 718, and finally ATI 718Plus (R) possessing the largest solidification interval in comparison.

The main focus of the present study was the influence of liquid metal properties on the particle size during water atomisation. Experiments for liquid iron showed that alloy additions of carbon and sulphur decreased the particle size. Moreover, it was indicated that the reduced d₅₀ value at increased %C and %S may be related to a decreased viscosity and surface tension respectively. An alternative mechanism could be that raised superheats at increased carbon contents increased the total available time for atomisation. This may also have decreased the particle size. The influence of surface tension and viscosity on the d₅₀ value was further analysed with a theoretical d₅₀ model proposed in a previous work. A reduced viscosity from 4∙9 to 2∙1 mPa s decreased the d₅₀ value with 33%. In addition, the particle size was estimated to decrease with 21% by decreasing the surface tension from 1840 to 900 mN m^-1.

The main focus of the present study was the influence of liquid metal properties on the particle size during water atomisation. Experiments for liquid iron showed that alloy additions of carbon and sulphur decreased the particle size. Moreover, it was indicated that the reduced d50 value at increased %C and %S contents may be related to a decreased viscosity and surface tension respectively. An alternative mechanism could be that raised superheats at increased carbon contents increased the total available time for atomisation. This may also have decreased the particle size. The influence of surface tension and viscosity on the d50 value was further analysed with a theoretical d50 model proposed in a previous work. A reduced viscosity from 6.8 to 4.3 mPa s decreased the d50 value with 33%. In addition, the particle size was estimated to decrease with 27% by decreasing the surface tension from 1 850 to 900 mN m-1.

This work aims to investigate how some significant atomising parameters influence the mass median particle size d₅₀ of water atomised metal powders. More specifically, these were water pressure, melt flowrate, water jet angle, liquid metal viscosity and surface tension. Existing models for the prediction of d₅₀ during water atomisation were reviewed. The selected models were fitted and compared with atomising experiments of liquid iron containing 0.5–4.4%C. Experimental results and model calculations were used in a parameter study to investigate how the different parameters influenced d₅₀. The effect on d₅₀ was large for the water pressure, medium for the viscosity and low for the melt flowrate and surface tension. Model calculations indicate that the jet angle has a large effect on d₅₀, which should be verified by additional studies. The model proposed by Bergquist (B. Bergquist: Powder Metall., 1999, 42, 331–343) showed the best agreement with the current experimental data.

A two-dimensional non-steady state computational fluid dynamic model was employed to gain a basic understanding of the flow in the ingot during casting. The surface velocity was found to be affected by the inlet angle and was found to vary with the casting level. The information of surface velocity was related to the probability of the inclusion removal. Water model experiments were also conducted to help the understanding. The model calculation revealed the same trends as the results of water model experiments. Both computational fluid dynamic data and the physical modelling showed that the inlet angle of 5 degrees currently used in the industry was a good alternative regarding inclusion removal. The present work suggests strongly that the melting shop should try to obtain a liquid or semiliquid film at as early stage as possible in ingot casting.